Abdominal Pain and Bowel Obstruction Mike Goodwin CRASH Course October, 2010

Abdominal Pain - Approach History Physical Labs Imaging Provisional Dx

History PQRST AAA etx But don’t forget PSx Bowel/Gyne/Urol ROS

Physical Exam Complete General appearance/vitals/H+N/Chest Abdo: Rigidity Rebound Guarding IPPA DRE / Pelvic / Groin / Flank-CVA

Labs Everyone: CBC, lytes BUN Cr LFT, Bili, Amylase/Lipase, lactate Urinalysis Urine Preg

Imaging AXR 3-views Free air Distended bowel/air-fluid Calcifications (panc or kidney/ureter) US If GS disease suspected Lower abdo pain in female

Imaging CT Abdo Test of choice for most patients Protocols to minimize contrast nephropathy

Bowel Obstruction: Overview History Etiology Pathophysiology Clinical presentation Imaging Management Special considerations

Causes of Small Bowel Obstruction in Adults Lesions Extrinsic to the Intestinal Wall    Lesions Intrinsic to the Intestinal Wall    Intraluminal/Obturator Obstruction   

Lesions Extrinsic to the Intestinal Wall Adhesions (usually postoperative)   Neoplastic Carcinomatosis   Extraintestinal neoplasms   Hernia  External (e.g., inguinal, femoral, umbilical, or ventral hernias)  Internal (e.g., congenital defects such as paraduodenal, foramen of Winslow, and diaphragmatic hernias or postoperative secondary to mesenteric defects Intra-abdominal abscess

Lesions Intrinsic to the Intestinal Wall Congenital   Malrotation   Duplications/cysts   Inflammatory   Crohn’s disease   Infections   Tuberculosis  Actinomycosis   Diverticulitis Neoplastic   Primary neoplasms   Metastatic neoplasms Traumatic  Hematoma   Ischemic stricture   Miscellaneous   Intussusception   Endometriosis  Radiation enteropathy/stricture

Intraluminal/Obturator Obstruction Gallstone    Enterolith    Bezoar

Common causes of small bowel obstruction in industrialized countries.

Pathophysiology Early: Increased motility & contractility Bowel dilation, fluid/lytes accumulate in lumen and bowel wall Third spacing, intravascular volume depletion

Bowel obstruction Increased intraluminal pressure Decreased mucosal blood flow Progressive Ischemia Perforation & Peritonitis

Clinical Diagnosis History Colicky abdominal pain Nausea / vomiting Abdominal distension Failure to pass flatus / feces

Physical Examination Vitals: Tachycardia, hypotension Abdomen: Distension Surgical scars Bowel sounds, increased or decreased Localized tenderness / rebound / guarding suggests strangulation Hernia exam (ventral, groin, etc) Rectal exam: Rectal masses Blood – suggesting ischemia, malignancy

Radiology Plain Abdo X-Rays Confirm Diagnosis Localize obstruction to small bowel or colon Evidence of complete or incomplete

Figure 46-13  Plain abdominal radiographs of a patient with a complete small bowel obstruction. A, Supine film shows dilated loops of small bowel in an orderly arrangement, without evidence of colonic gas. B, Upright film shows multiple, short, air-fluid levels arranged in a stepwise pattern.  (Courtesy of Melvyn H. Schreiber, M.D., The University of Texas Medical Branch.)

*Suggests ischemia/strangulation Plain X-ray Features Dilated Small Bowel (>3 cm) Multiple air-fluid levels Colonic gas pattern Normal / Dilated (Ileus or partial obstruction) Absence of gas c/w complete obstruction *Thickened bowel wall *Pneumatosis intestinalis *Suggests ischemia/strangulation

Plain X-rays Lappas et al 2001 Review of 12 AXR findings with SBO Combination of Air-fluid levels of different heights in the same bowel loop Mean air-fluid level diameter of 2.5 cm or greater Most predictive of a high-grade partial or complete SBO

AXR Disadvantages 20-30% false negative rate Does not localize site of obstruction Does not establish etiology of obstruction

CT Scan 95% sensitive 96% specific 95% accurate in determining the presence of complete or high-grade SBO Shows site and cause of obstruction in 95% of instances Less accurate for partial SBO (50% some studies)

CT for SBO CT performed with IV and PO contrast High-grade SBO seen even with no contrast Lesser grades of obstruction seen with PO contrast IV contrast for assessment of bowel wall for signs of edema or ischemia.

CT Findings in Patients with Small Intestinal Obstruction Type of Obstruction Findings Simple obstruction, partial or complete Proximal bowel dilatation Discrete transition zone with collapsed distal small bowel No passage of oral contrast beyond the transition zone Little gas or fluid in colon

Figure 116-4 Abdominal computed tomography (CT) images of two patients with adhesive small bowel obstruction (SBO). The image on the left (A) shows fluid-filled loops of ileum proximal to a transition point at the site of obstruction (arrow); decompressed bowel is seen distal to the obstruction

CT Findings in Patients with Small Intestinal Obstruction Type of Obstruction Findings Closed-loop obstruction Bowel Wall Changes U-shaped, distended, fluid-filled bowel loop Whirl sign Beak sign Mesenteric Changes Radial distribution dilated bowel loops Thickened mesenteric vessels converging toward point of obstruction

Figure 116-6 Abdominal computed tomography (CT) images of patients with intestinal obstruction. A, A patient with a closed-loop obstruction in which the small intestine twisted around omentum that was adherent to the anterior abdominal wall (arrow). Note the massively dilated loops of contrast-filled proximal intestine on the right side of the abdomen and the fluid-filled loops of bowel containing no contrast on the left. In the center of the abdomen is a tightly twisted segment of bowel (“whirl sign”) consisting of the site of torsion with obstruction of the afferent and efferent limbs of the intestine. B, A patient with strangulated obstruction, evidence of which includes bowel wall thickening (blue arrow), mesenteric stranding (green arrow), and ascites (asterisk).

CT Findings in Patients with SBO Type of Obstruction Findings Strangulated Obstruction Bowel Wall Changes Bowel wall thickening Target sign Pneumatosis intestinalis Dec. bowel wall enhancement Mesenteric Changes Blurring of mesenteric vessels Obliteration of mesentery and vessels Engorgement of mesenteric vasculature Other Ascites

B, A patient with strangulated obstruction, evidence of which includes bowel wall thickening (blue arrow), mesenteric stranding (green arrow), and ascites (asterisk).

When to Order CT? Clinical presentation or abdominal films nondiagnostic Hx of abdominal malignancy Immediate postsurgical patients Patients who have no history of abdominal surgery

Barium / Contrast Studies History of recurring obstruction Low-grade mechanical obstruction Defines the obstructed segment and degree of obstruction

Gastrograffin Swallow in Adhesive SBO, Cochrane Review, 2004 Diagnostic Gastrofraffin seen in the cecum on AXR within 24 hours predicts resolution Sensitivity of 0.96, specificity of 0.96 Therapeutic Hospital length of stay 2-3 days shorter in non-operative patients Studies prospective, non-blinded

Simple Versus Strangulating Obstruction Classic signs: Fever WBC inc Constant Abdo pain But no parameters reliably detect strang. CT findings detect late ischemic changes

Treatment – Nonoperative Fluid resuscitation IV resuscitation with isotonic saline Electrolyte replacement Monitor urine output Tube decompression Empties stomach Reduces aspiration risk No benefit to long intestinal tubes In partial obstruction: 60-85% success rate

Treatment - Operative Complete obstruction Generally mandates operation Some have argued for nonoperative approach in selected patients 12-24hr delay of surgery is safe >24hr delay is unsafe

Operative Technique Dependent on underlying problem Adhesive band: Lysis of adhesions Incarcerated hernia: manual reduction and closure of defect *Presence of hernia with SBO mandates OR Malignant tumors: Difficult challenge Diverting stoma Resection / anastamosis Enteroenterostomy

Intestinal Viability at Surgery Release obstructed segment Place in warm sponge x 15-20 minutes If normal colour and peristalsis: return to abd Doppler probe adds little to clinical judgment (Bulkley, 1981) Fluorescein may be useful in difficult cases “Second look” in 24 hrs if questionable viability or if clinically deteriorates post-op

Laparoscopy in Acute SBO? Criteria: Mild distension Proximal obstruction Partial obstruction Anticipated single-band obstruction No matted adhesions / carcinomatosis

Special Considerations: Recurrent Adhesions Multiple agents have been tried, none successful Hyaluronate-based membrane shown to reduce severity of adhesion formation (Becker, 1996; Vrigland, 2002) No studies yet to show reduction in obstruction

Special Considerations: Recurrent Adhesions So far, best evidence to prevent adhesions is good surgical technique: Gentle handling of bowel Avoid unnecessary dissection Exclusion of foreign material from peritoneum Adequate irrigation / removal of debris Place omentum around site of surgery

Special Considerations: Acute Post-op Obstruction Obstructive symptoms after an initial return of bowel function and resumption of oral intake Technical complication versus adhesions CT scan useful to evaluate for complications: Anastamotic leak Narrow anastomosis Internal hernia Obstruction at stoma Early reoperation may be indicated

Acute Adhesive Postoperative Obstruction Difficult to distinguish from ileus Incidence 0.7% Highest incidence on small intestine (3% – 10%) Present as early as POD 4 Usually partial SBO CT preferred modality

Acute Postoperative Obstruction (Adhesive) 80% spontaneous resolution of symptoms 4% of patients required more than 2 weeks of treatment SBO after laparoscopy: suspect hernia at trocar site

Surgery for Malignant Bowel Obstruction in Advanced Gynaecological and Gastrointestinal Cancer Cochrane Review:2004 Role of surgery controversial No firm conclusions from many retrospective case series Control of symptoms varies from 42% to over 80 Rates of re-obstruction, from 10-50%, though time to re-obstruction was often not included Continues to be a challenging problem

Steroids in Advanced Gyne/GI Cancer With SBO Cochrane Review of prospective data (89 patients) Trend, not statistically significant, for resolution of bowel obstruction using corticosteroids No statistically significant difference in mortality NNT 6 Morbidity associated with steroids appears low

Guidelines for Operative and Nonoperative Therapy Summary Guidelines for Operative and Nonoperative Therapy

Emergent Operation Incarcerated, strangulated hernia Peritonitis Pneumatosis Pneumoperitoneum Suspected / proven strangulation Closed-loop obstruction Complete bowel obstruction

Urgent Operation Progressive bowel obstruction after conservative measures started Failure to improve with conservative therapy in 24-48 hours Early post-op technical complications (not adhesions)

Operation Usually Delayed Safely Postoperative adhesions Immediate post-op obstruction (adhesive) Acute exacerbation of Crohn’s dx, diverticulitis, radiation enteritis Chronic, recurrent partial obstruction

Large Bowel Obstruction Cancer Cancer (>90%) Other things Sigmoid Volvulus (5%) Diverticular Disease (3%)

Large Bowel Obstruction Approach Contrast Enema CT Abdo Treat underlying cause

Acute Pseudo-Obstruction Common ward consult Predisposing Conditions: Surgery Trauma Infection Cardiac (CHF/MI) Neurological (PD, SCI, MS, AD Metabolic (↓K/Na)

Ogilvie’s Syndrome Meds Assoc w/Ogilvie’s Narcotics Anticholinergic TCA Chlorpromazine Levodop Ca++ blockers Clonidine  Ogilvie’s Initial Tx: Correct fluid and lyte NPO/NG Rectal tube Limit offending medications >80% success

Ogilvie’s Treatment Neostigmine 2 mg IV Atropine at bedside Monitored bed Patient supine, on bedpan  90% success rate Colonoscopy If neostigmine fails Decompression Surgery Last resort; rarely needed If ischemia/perforation